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Neuromodulation is a technique that uses electrical or chemical signals on specific nerve pathways in your body to change the way they carry information. Researchers are exploring a type of neuromodulation called vagus nerve stimulation (VNS) as a way to repair nerve damage in multiple sclerosis (MS).

The defining marker of MS is that it causes damage to myelin, the protective sheath that covers your brain and spinal cord nerves. Without myelin, your nerves can’t transmit messages to and from your body correctly. This can cause issues with your vision, movement, and ability to feel things that come in contact with your body (sensation).

At the 2025 Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum in late February, Cristin Welle, PhD, professor of neurosurgery, physiology and biophysics and vice chair for research in neurosurgery at the University of Colorado Anschutz Medical Campus, presented research that suggests there may be a way to repair myelin and get back some of its function with VNS....

Results of Animal Studies

The research started with mice whose DNA had been altered to express a fluorescent protein in the cells that make myelin (oligodendrocytes). By removing a piece of the mice’s skulls and putting a glass window in its place, the researchers could watch what happens over time with these cells as they stimulate the vagus nerve.

For three weeks they fed the mice a toxin that specifically kills oligodendrocytes while imaging their brains every two to three days to see which cells die. Then they stop the toxin.

Welle says the brain already has oligodendrocyte stem cells (precursor cells) that form new cells when the old ones die, but the process doesn’t go far on its own.

“There's a capacity to regenerate oligodendrocytes and myelin, but for whatever reason, both in mice and in humans, after an injury like this, the repair process is not complete, meaning that you only recover about 50% of the oligodendrocytes that you started with,” says Welle.

The team then had the mice learn a new motor task (reaching for food pellets) for seven days. This task by itself encouraged about 15%-20% more oligodendrocyte recovery than in mice that didn’t do the motor task. But in a separate group, mice learned this motor task while having vagus nerve stimulation with every successful reach (called “paired” stimulation). The result:

“They recovered considerably more oligodendrocytes — close to full recovery,” says Welle. “It's strange that you would stimulate the periphery and see this robust effect on myelin recovery in the brain. But that is what we found.”...